Starter gearing for internal combustion engines



Jan. 7, 1958 J. J. SABATINI 2,818,735

. STARTER GEARING FOR INTERNAL COMBUSTION ENGINES Filed Feb. 25, 1956 2 Sheets-Sheet 1 lNiENToR. Jphn/J A TORNE Y WITNESS:

Jan. 7,1958

J. J. SABATlNl STARTER GEARING FOR INTERNAL COMBUSTION ENGINES Filed Feb. 23. 1956 2 Sheets-Sheet 2 WITNESS.

INVENTOR (5 BY I TORNEY United States Patent STARTER GEARlN G FOR INTERNAL COMBUSTION ENGINES John J-.;.Sabatini, Horseheads, N. Y., assignor to Bendix Aviation Corporation, Elmira Heights, N. Y., a corporation of Delaware Application February 23, 1956, Serial No. 567,354

6 Claims. (Cl. 747) vThe present invention relates to starter gearing for internal combustion engines and more particularly to that. type. in which engagement of the gearing is brought about automatically by energization of the starting motor, disengagement taking place when the engine starts and overruns the starting motor.

It is an object of the present invention to provide a novel starter gear of the above type in which the meshing operation takes place reliably in spite of adverse conditions such as, the presence of congealed lubricant, and/ or accumulations of dust or other foreign matter.

It is another object to provide such a device including electro-magnetically actuated means for positively moving a motor driven pinion into initial mesh with a gear on the engine to be started.

It is another object to provide such a device including further means for completing the meshing movement of the pinion and for rotating the pinion, which means is operative to disconnect the initial meshing means.

Further objects and advantages will be apparent from the following description taken in connection with the accompanying drawing in which:

Fig. 1 is a side elevation, partly broken away and in section, showing a preferred embodiment of the invention with the parts in idle position;

Fig. 2 is a view similar to Fig. 1 showing the parts in the positions assumed upon initial energization of the starting motor, with the mesh-enforcing detent in operative position;

Fig. 3 is a similar view at an intermediate point in meshing operation; and

Fig. 4 is a similar view showing the parts in the positions assumed during cranking.

In Fig. 1 of the drawing there is illustrated a motor shaft 1 extending through a bearing 2 of the starting motor, and supported at its outer end in an outboard bearing 3 of the motor housing. The commutator 4 and armature 5 of the starting motor are fixedly mounted on the motor shaft in the usual manner and the armature 5 is normally maintained in a position shifted slightly to the right of its centered relation to the field coils 6 of the motor by means of a spring washer 7 located on the motor shaft 1 between the commutator 4 and the bearing 2. The remaining structure of the starting motor is conventional, and is therefore not illustrated.

A screw shaft 8 is fixedly mounted on the motor shaft 1 in any suitable manner as by means of a cross pin 9, and has threaded thereon a control nut and driving coupling member if. Coupling member 11 is provided with inclined driving projections 12 adapted to cooperate with similar projections 13 on a driven coupling member 14 loosely surrounding the screw shaft. Driven coupling member 14 has overrunning clutch teeth 15 cooperating with similar teeth 16 on a clutch member 17 rigidly mounted on a pinion 18 which is slidably journalled on the motor shaft 1 for movement into and out of mesh with an engine gear 19. A barrel member 21 surrounding s lCti the control nut and coupling members in spaced relation thereto has an inturned flange 22 engaging a flange 23 on the driven coupling member 17, and is externally threaded as indicated at 24 for the reception of a detent member 25 in the form of a nut threaded thereon. Detent member 25 is provided with overrunning'clutchteeth 26 which are adapted to cooperate with similar teeth 27 on. a fixed motor frame member 28, but normally spaced therefrom by reason of the displaced position of the motor shaft 1- by the spring 7. A split lock ring 29 on the barrel member 21 limits relative displacement of the detent nut 25 to the left thereon.

A detent positioning member in the form of a sleeve 31 is fixedly mounted on the screw shaft 8 as by means of the cross pin 9, and has a stop ring 32 fixedly mounted thereon in position to engage a flange member 33 rigidly mounted in the detent nut 25 in any suitable manner to thereby define the idle position of the detent nut. The flange member 33 is yieldingly urged toward the stop ring 32 by a spring 34 confined on the sleeve 31 by a terminal-flange .35.

'Means for yieldingly limiting the separation of the coupling members 11, id is provided comprising a coupling spring 36 formed of a plurality of heavy spring rings hearing at one end against a flange 3'7 on the :coupling member 11, and at the other end on a thrust plate 38 confined in the barrel member 21 by a thrust ring 39, and having a splined connection as indicated at 41 with the coupling member 11. In order to normally maintain the overrunning clutch teeth 15, 16 in engagement a light compression spring 42 is interposed between the flange 37 on coupling member 11 and a flange 43 on the driven coupling member 14. Preferably, the flange 43 has a sliding hearing within the barrel 21 in order to maintain the driven coupling member 14 in centered position.

In operation, starting with the parts in the positions as illustrated in Fig. 1, energization of the starting motor causes the field coil 6 to draw the armature 5 into centered relation therewith, thereby shifting the motor shaft 1 to the left and bringing the teeth 26 of the detent nut 25 into engagement with the teeth 27 of the motor frame member 28 as shown in Fig. 2. Simultaneously with this movement, rotation of the motor shaft 1 is transmitted to the screw shaft 8, and if the threads of the screw shaft and the control nut 11 are free from congealed lubricant, and there is no obstruction to the longitudinal movement of the pinion 18, the rotation of the screw shaft 8 will traverse the control nut 11, coupling member 14 and pinion 18 to the right, causing the pinion to mesh with the engine gear 19. If, however, such action does not take place freely for any of the reasons above given, the control nut and driving clutch member 11 may rotate with the screw shaft, and this rotation is transmitted through the splined plate 38 to the barrel member 21. Since at this time the detent nut 25 is prevented from rotation by its clutching engagement with the motor frame member 28, rotation of the barrel member 21 causes it to be positively traversed to the right, drawing with it the control nut 11 by means of the spring 36, and consequently causing the pinion 18 to be moved into initial meshing relation with the engine gear 19. As soon as this happens, rotation of the pinion and consequently of the control nut 11 is prevented, so that continued rotation of the motor shaft 1, causes further traversal due to the screw-jack action of the screw shaft 8 and control nut 11, whereupon the detent nut 25 is drawn out of engagement with the motor frame member 28 as illustrated in Fig. 3.

Meshing then proceeds until the movement of the control nut on the screw shaft 8 is arrested by encountering 3 the ends 44- of the threads on the screw shaft, whereupon cranking takes place in the usual manner, the shock of initial rotation being taken up by sliding movement of the inclined coupling teeth 12, 13 as indicated in Fig. 4 of the drawing.

When the engine starts, the parts are returned to their idle positions by the overrunning action of the drive pinion in the usual manner, the motor shaft 1 being returned to its decentered idle position as shown in Fig. 1 by the spring 7 irrespective of energization of the starting motor since at this time the rapid rotation of the starting motor reduces the strength of the field coils 6 to a comparatively low value.

Although but one form of the invention has been shown and described in detail it will be understood that changes may be made in the design and arrangement of the parts without departing from the spirit of the invention as defined in the appended claims.

I claim:

1. In an engine starter drive a motor including a stationary field and an armature mounted on a rotary shaft, a hollow screw shaft fixed thereon, a control nut threaded on the screw shaft, a pinion slidably journalled on the motor shaft for movement into and out of mesh with a gear of the engine to be started, means for coupling the pinion to the control nut; said motor shaft being mounted with freedom for limited longitudinal movement, yielding means biasing the motor shaft axially away from its normal operative position and means rendered operative by longitudinal displacement of the motor shaft responsive to the mutual attraction of the field and armature when the motor is energized for positively traversing the pinion into partial mesh with the engine gear responsive to rotation of the motor shaft.

2. An engine starter drive as set forth in claim 1 in which said coupling means comprises a barrel member and said traversing means includes a detent member threaded on said barrel member.

3. An engine starter drive as set forth in claim 2 in which said detent member is moved into engagement with a stationary member by said longitudinal displacement of the motor shaft.

4. An engine starter drive as set forth in claim 3 including yielding means normally maintaining the motor shaft in position to hold the detent member free from the stationary member.

5. An engine starter drive as set forth in claim 3 including further means responsive to the final meshing movement of the barrel member for withdrawing the detent member from the stationary member.

6. An engine starter drive as set forth in claim 5 including further yielding means mounted on the screw shaft urging the detent member toward its normal position axially of the motor shaft.

References Cited in the file of this patent UNITED STATES PATENTS 

